Vitamin B₁₂ deficiency can be sneaky and harmful

What harm can having too little of vitamin B₁₂ do? Consider this: Over the course of two months, a 62-year-old man developed numbness and a "pins and needles" sensation in his hands, had trouble walking, experienced severe joint pain, began turning yellow, and became progressively short of breath. The cause was lack of vitamin B₁₂ in his bloodstream, according to a case report from Harvard-affiliated Massachusetts General Hospital published in The New England Journal of Medicine. It could have been worse—a severe vitamin B₁₂ deficiency can lead to deep depression, paranoia and delusions, memory loss, incontinence, loss of taste and smell, and more.

Why vitamin B₁₂ is important

The human body needs vitamin B₁₂ to make red blood cells, nerves, DNA, and carry out other functions. The average adult should get 2.4 micrograms a day. Like most vitamins, B₁₂ can't be made by the body. Instead, it must be gotten from food or supplements.

And therein lies the problem: Some people don't consume enough vitamin B₁₂ to meet their needs, while others can't absorb enough, no matter how much they take in. As a result, vitamin B₁₂ deficiency is relatively common, especially among older people.

Are you at risk of vitamin B₁₂ deficiency?

There are many causes for vitamin B₁₂ deficiency. Surprisingly, two of them are practices often undertaken to improve health: a vegetarian diet and weight-loss surgery.

Plants don't make vitamin B₁₂. The only foods that deliver it are meat, eggs, poultry, dairy products, and other foods from animals. Strict vegetarians and vegans are at high risk for developing a B₁₂ deficiency if they don't eat grains that have been fortified with the vitamin or take a vitamin supplement. People who have weight-loss surgery are also more likely to be low in vitamin B₁₂ because the operation interferes with the body's ability to extract vitamin B₁₂ from food.

Conditions that interfere with nutrient absorption, such celiac or Crohn's disease, can cause B₁₂trouble. So can the use of commonly prescribed heartburn drugs, which reduce acid production in the stomach (acid is needed to absorb vitamin B₁₂). The condition is more likely to occur in older people due to the cutback in stomach acid production that often occurs with aging.

Vitamin B₁₂ deficiency symptoms

Vitamin B₁₂ deficiency can be slow to develop, causing symptoms to appear gradually and intensify over time. It can also come on relatively quickly. Given the array of symptoms a vitamin B₁₂ deficiency can cause, the condition can be overlooked or confused with something else. Vitamin B₁₂deficiency symptoms may include:

• strange sensations, numbness, or tingling in the hands, legs, or feet
• difficulty walking (staggering, balance problems)
• anemia
• a swollen, inflamed tongue
• difficulty thinking and reasoning (cognitive difficulties), or memory loss
• weakness
• fatigue

While an experienced physician may notice the symptoms and be able to detect a vitamin B₁₂ deficiency with a good interview and physical exam, a blood test is needed to confirm the condition.

It's a good idea to ask your doctor about having your B₁₂ level checked if you are a strict vegetarian or have had weight-loss surgery or have a condition that interferes with the absorption of food.

Early detection and treatment is important. If left untreated, the deficiency can cause severe neurologic problems and blood diseases.

Boosting your B₁₂

A serious vitamin B₁₂ deficiency can be corrected two ways: weekly shots of vitamin B₁₂ or daily high-dose B₁₂ pills. A mild B₁₂ deficiency can be corrected with a standard multivitamin.

In many people, a vitamin B₁₂ deficiency can be prevented. If you are a strict vegetarian or vegan, it's important to eat breads, cereals, or other grains that have been fortified with vitamin B₁₂ or take a daily supplement. A standard multivitamin delivers 6 micrograms, more than enough to cover the average body's daily need.

What vitamin B₁₂ can't do

The internet is full of articles lauding the use of vitamin B₁₂ to prevent Alzheimer's disease, heart disease, and other chronic conditions or reverse infertility, fatigue, eczema, and a long list of other health problems. Most are based on poor or faulty evidence.

Take Alzheimer's disease as an example. Although there is a relationship between low vitamin B₁₂ levels and cognitive decline, clinical studies—including those involving people with Alzheimer's disease—have not shown improvement in cognitive function, even doses of vitamin B₁₂ as high as 1000 micrograms per day.

For now, it's best to get enough vitamin B₁₂ to prevent a deficiency, and not look to it as a remedy for what ails you.

Adapted from a Harvard Health Blog post by Patrick Skerrett.